Computer simulation has revolutionized science and engineering. The PIs propose to establish a National Center for Simulation in Rehabilitation Research to bring the power of simulation to medical rehabilitation. The Center will provide robust tools for simulating human motion, enabling investigators to answer clinical questions that cannot be solved with experimental studies alone. Hundreds of scientists affiliated with the Center will focus on critical areas of rehabilitation, including stroke, spinal cord injury, cerebral palsy, osteoarthritis, prosthetics, orthotics, and sports medicine. The PIs will pursue the following specific aims. 1. Develop and disseminate advanced technology for the simulation of musculoskeletal dynamics and accelerate its appropriate use in rehabilitation research. 2. Award seed grants to innovative and meritorious pilot projects that employ simulation tools to identify the mechanisms underlying movement disorders and improve the efficacy of rehabilitation. 3. Attract and train 20 talented scholars from computer science, biomechanics, physical therapy and other fields to become experts in simulation and the needs of individuals with disabilities. 4. Teach over 300 rehabilitation scientists to create and test biomechanical simulations and correctly interpret their results during intensive multi-day workshops. 5. Introduce over 1000 rehabilitation specialists to the value and limitations of musculoskeletal simulation through hands-on training at national and international conferences. 6. Create web-based tutorials, lectures, and a formal textbook to promote the appropriate use of simulation in rehabilitation research. The development and dissemination of open source software for the rehabilitation community addresses a critical barrier to progress in the field. The software will be designed in close partnership with rehabilitation scientists and physicians to address critical, clinically motivated questions across the spectrum of medical rehabilitation. There is a rapidly growing community of rehabilitation scientists eager to engage in this project; thus, the timing for establishing this core resource is excellent.